In general, electronic devices such as a liquid crystal display and a semiconductor device are manufactured by forming patterns of many layers on a substrate. In order to form the patterns, until now, a photolithography process has been frequently used. However, the photolithography process has a problem in that the manufacturing process is complicated and a large amount of chemical waste hazardous to the environment is generated because a predetermined pattern mask needs to be manufactured and a process of chemical etching and stripping needs to be repeated. Due to the problems, the manufacturing costs are increased and thus the competitiveness of products deteriorates. As a new method of forming patterns for solving the disadvantages of the photolithography process, a roll printing method using a printing roll is proposed.
The roll printing method comprises various methods, but may be largely divided into two types of a gravure printing method and a reverse offset printing method.
The gravure printing method is a printing method in which printing is performed by smearing ink on a concave plate and removing the remaining ink and known as a method suitable for printing in various fields such as publishing, packaging, cellophane, vinyl, and polyethylene, and researches for applying the gravure printing method to manufacture active elements or circuit patterns applied to the display devices have been conducted. In the gravure printing method, since the ink is transferred onto the substrate by using a transfer roll, even in a large-area display device, patterns may be formed through one transfer by using a transfer roll corresponding to an area of the desired display device. The gravure printing method may be used for forming an ink pattern for a resist on the substrate and patterning various patterns of the display device, for example, metal patterns for a gate line and a data line which are connected with the TFT, a pixel electrode, and a capacitor as well as a TFT in the case of a liquid crystal display device.
However, generally, a blanket used in the gravure printing method is manufactured by casting a silicon-based resin in a hard master mold, and there is a limit in manufacturing the blanket manufactured above to have a uniform thickness and it is difficult to mass-produce the blanket with a pilot scale. As a result, in order to precisely form fine patterns, the reverse offset printing method is mainly adopted.